Oregon group planning nation's first tsunami evacuation structure

June 02, 2009

CANNON BEACH, Ore. – A group of university experts, state and federal officials, and local residents in the coastal town of Cannon Beach, Ore., are working together to create a new city hall – but more importantly, the first structure in the United States ever built specifically to survive the force of a tsunami.

A report on the issue has been completed, research programs at Oregon State University will do further studies this summer, and a conference is planned for this fall. The project goes to the heart of an issue of increasing urgency in the Pacific Northwest – what do you do when a major earthquake hits and a tsunami is imminent, but in the few minutes available there may not be time to run to high ground?

“We’ve already done a lot with public education to alert people in high risk zones about major earthquakes and tsunamis, and what to do,” said Harry Yeh, the Edwards Professor of Coastal and Ocean Engineering at OSU. “Those efforts are important and we’ll continue them. But at some point, knowing what to do may not be good enough if you don’t have the time to do it.”

The Cascadia Subduction Zone off the coast of Oregon, Washington and northern California causes enormous earthquakes that – depending on location – occur about every 220 to 525 years, along with associated tsunamis. Researchers believe the last such event occurred in 1700, causing a tsunami of such magnitude that it hit not only local shores but swept across the Pacific Ocean to Japan.

An updated study by the Oregon Department of Geology and Mineral Industries (DOGAMI) recently doubled the area in Cannon Beach that might be inundated by a tsunami, including almost all the commercial areas in this small city which has about 1,700 residents – not including the thousands of tourists that might be present on some days.

A subduction zone earthquake could be followed by a major tsunami 10-20 minutes later, experts say, while people are surrounded by collapsed buildings, blocked roads, traffic jams and possibly failed bridges. In the few minutes available – at this and many other coastal locations – the concept of “vertical evacuation” to the roof of a tall structure that would withstand the coming tsunami might offer the only realistic chance of survival for some people.

“Strong, reinforced concrete buildings can often survive a tsunami, we saw that in Indonesia in 2004,” Yeh said. “That event was very geologically similar to what we expect in the future of the Pacific Northwest, and it taught us a lot of lessons. Unfortunately, in East Asia those lessons came at a cost of 230,000 lives.”

OSU researchers, through their expertise with structural engineering, modeling and the world’s most sophisticated Tsunami Wave Basin, hope to help prevent a repetition of the Indonesian disaster for the people of Cannon Beach and many other coastal cities. They will work closely with officials at DOGAMI and others who are leading this broad state and community effort.

“We know we can build a structure, usually with an open first story that could be used for parking or other community events, that will survive an earthquake and tsunami,” Yeh said. “Everyone agrees it would be good to have, but it will cost more. A realistic engineering and research goal is to find ways to bring those costs down as much as we possibly can, through our improved understanding of tsunami run-up forces. And we must ensure the building is strong enough to do its job – which is saving lives.”

If the project in Cannon Beach actually comes to fruition and the structure is built, Yeh said, it could form a model for other similar structures in many vulnerable coastal areas of the United States and around the world.

Jay Raskin, an architect, local resident and community leader in Cannon Beach, has led efforts there to embrace this project.

“Ever since the research made clear the risks we face in Cannon Beach from earthquakes and tsunamis, we’ve been interested in trying to do something to address this problem,” Raskin said. “We need a new city hall here, and we need to protect our community. A structure like this could help protect people’s lives in the event of a tsunami and give us a starting point around which to maintain government services and rebuild.”

Raskin said a design team that he helped organize will involve university, state, federal and private industry experts. Work will also be done to engage more community residents in the discussion, even though the city has been a coastal leader in tsunami education and preparation since the 1990s.

“There is general public support for creating a new city hall that is also a tsunami refuge,” Raskin said. “But there are also a lot of questions about how such a building would work both day-to-day and in an emergency, and how much it would cost. We need to be able to answer these questions so the public can weigh the benefits and risks to make an informed decision.”

Tsunami-resistant architecture, experts say, could be incorporated into a range of public structures such as city halls, convention centers, schools, or libraries, and conceptually even private buildings that meet the requirements. In Cannon Beach, a building is envisioned that would provide elevated refuge for 800 to 1,000 people.

To serve their purpose, these types of buildings would have to be able to withstand a major earthquake, have deep foundations, be at least two stories high, usually incorporate barrier walls to help dissipate wave forces, have a roof available for emergency evacuation, and meet other requirements. They would be of special value in any coastal community with a high level of visitors, many elderly residents or children, or where higher ground is a sufficient distance away that it may not be practical to reach it in the time available.

In Oregon, about 100,000 residents are in the tsunami inundation hazard zone every day, officials say, some with long travel distances to higher land.

A two-day workshop bringing together a range of university, community, state, federal and private experts will be held on Sept. 28-29 to further explore the Cannon Beach plans, with a field trip to the coast and a meeting in Portland.

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